Interestingly, chromosome X loss is seen in 80% of females with group 4 medulloblastomas (8) Groups 3 and 4 medulloblastomas have recently been shown to have EZH2 and KDM6A alterations which are involved in histone methylation (specifically H3K27) (34, 35). The gene discussed is EZH2; the disease is medulloblastoma.